DNSServer cleanup

[Makuna]

Basic Infos

DNSServer does not have a destructor which can cause memory leaks if dynamically allocated.

Problem Description

DNSServer needs a destructor. Currently you can destruct the object and leave the internal _buffer memory still allocated causing a memory leak.

This can be worked around by calling stop() before destructing, but this is an unsafe assumption.

p.s. This library also lacks the keywords file so there is no pretty colors in the Arduino IDE for the methods.

[earlephilhower]

I'm not seeing any leak potential.

_buffer is only malloc()'d in DNSServer::processNextRequest()

Arduino/libraries/DNSServer/src/DNSServer.cpp

Line 55 in 6314093

_buffer = (unsigned char*)malloc(_currentPacketSize * sizeof(char));

It's free()'d inside the same if {...} statement before any potential return from the method:

Arduino/libraries/DNSServer/src/DNSServer.cpp

Line 73 in 6314093

free(_buffer);

If you've got the time, PRs for things like keywords.txt are always appreciated, too.

[Makuna]

Wow, I looked deeper, and you are correct. The code in the stop() should never be needed then and should be removed as it implies a use that is not present.

Having the destructor call stop would be still be a good thing.

Further, there should not be a member at all for the _buffer, since it has a limited lifetime, it should just be passed into the methods that will need it rather than store an extra pointer for the lifetime of the object to just avoid passing an argument.

[devyte]

@Makuna there's also my ESPAsyncDNSServer in case you're interested. I only mention it because I've received little feedback, andand I'd like some :p

[devyte]

@Makuna you self-assigned this. Do you intend to get it done within the next few days?

[Makuna]

#5194